Multi-user multiple-input multiple-output (MU-MIMO) technology enables sending different traffic to multiple client devices simultaneously. Multi-user grouping refers to selecting client devices from a plurality of client devices to form a group for sending different traffic to the selected client devices simultaneously. A scheduler provides a mechanism for selecting which data to send to which user(s) in a given time slot. Airtime fairness in a wireless environment is an attempt to allot airtime between competing client devices in an equitable manner while taking into account the various priorities of the traffic associated with the client devices. Airtime fairness may be applied to other multi-user simultaneous communication technologies, for example, but not limited to, orthogonal frequency-division multiple access (OFDMA), which is a multi-user version of the popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users. This allows simultaneous low-data-rate transmission from several users.